This invention relates to a device for anchoring one end of a stay to a base, generally called an anchor head.
Designated by stay is particularly, but not exclusively, a cable used for the construction of suspended and stayed structures, such as suspension bridges, cable-stayed bridges, stadium roofs, buildings, telecommunications towers, etc.
A stay could also be a cable used for an earth anchor. An earth anchor includes a steel tension member, or members, sheath encased and embedded in a hardenable material such as mortar grout poured in a bore hole prepared in the ground.
Such a stay allows parts of a structure to be connected where bases for the anchoring of the ends of this stay have been created beforehand, each through the agency of a device designed for this purpose.
The invention also relates to a method for creating a device of the aforementioned type.
The invention relates more specifically to a device for the anchoring of one end of a stay to a base, this end of the stay comprising at least two strands which diverge from the longitudinal axis of the stay in such a way as to become anchored in the device, the strands each being generally made up of a metallic core wire and a protective sheathing, the device itself being intended to be positioned and immobilised in translation in a bore provided in said base.
To anchor the stay to the base, one starts by mounting the anchoring device on the base in the shouldered bore, then in this device one engages, then immobilises, the ends concerned, one by one, of the strands.
Such a device comprises a first rigid unit which:
is delimited transversally by a cylindrical face and longitudinally by two opposite faces, substantially orthogonal to the longitudinal axis of said first unit,
is traversed by perforations which, made substantially parallel to the longitudinal axis of the unit, are each intended for passage of one end, devoid of sheathing, of a strand, and each including a bearing surface intended to co-operate with an immobilisation piece of such an end devoid of sheathing,
bears at least one tubular element to cover, over a certain distance measured from one of its opposite faces, the bundle of strands in a water-tight way at least in its part where the strands are devoid of sheathing.
In this type of device, the length of the tubular element, referred to as the transition pipe, is such that it makes the device cumbersome to mount.
In the prior art, to place the device in the bore of the base and abutting against the shouldered face of this bore, it often happens that it is not possible to mount it by engaging it in the bore, against its shouldered face.
In the prior art, the mounting must be achieved in reverse manner, that is to say in a direction opposite to that in which the stay must be stressed, and stops, clamping jaws making up a so-called split shim, must be installed around the device to allow it to find, ultimately, support against the shouldered face of the bore.
These technical features increase the manufacturing price of these creations.
One object of the invention is to obtain an anchoring device which overcomes this drawback.
Likewise a drawback with the state-of-the-art devices is that the ends of the strands which have had their sheathing removed are not protected against oxidation through the device during the entire duration of mounting, which can amount to between several hours and several months.
In fact, the strands are mounted one by one, and the tubular element which must finally cover the bundle of strands in a water-tight way does not ensure individual protection of these strands during their mounting.
One solution can consist in protecting the strands by metallisation, but this method increases the manufacturing cost.
An object of the invention is to obtain a device which makes it possible to protect the part of each strand devoid of sheathing against oxidation during and after installation of the strands.
An additional object of the invention is to obtain a device which can be prefabricated without posing problems with respect to transport to the place of utilisation and subsequent mounting on the base.
Another object of the invention is to obtain a device which makes it possible to damp the vibrations and bending constraints of each strand, and this individually.
Another object is to obtain a device in which it is possible to check the system of protection for each strand during service.
Finally, a further object of the invention is to obtain a device of standardised length.
To achieve these objects, the invention has as its subject matter a device of the aforementioned type, in particular characterised in that, in the state of being separated from the base, the device comprises a second substantially cylindrical, rigid unit which:
is rigidly connected to said first unit,
has at least two independent channels which, running substantially parallel and in each case in the prolongation of a perforation of the first unit, each have the one of their ends connected in a water-tight way to the first unit and the other having,
a first locally water-tight pressing surface around the sheath covering the core wire of a strand, when it is engaged in the channel,
a second surface of lateral support for the sheath of a strand in view of the deviation of said strand from the axis of the channel, which receives it, toward the axis of the end of the stay.